I have a 1985 4runner. 22re, automatic. When I press the pedal to the floor it doesn't always shift down, and when I'm just generally accelerating it seems to shift into 4th gear too soon. It takes off just fine but once I get up in speed it shifts up and just "gargles" along with not much power. Any suggestions? Also seems to have a little "pop" when it idles, is this oxygen sensor?